[15AcreWoods]

I found a formula how to figure bullet energy. Multiply the bullet weight by the velosicity. Square the result, in other words multiply the result by itself and then divide by a constant of 450450.

(V * W)*(V * W) / 450450 = energy in foot pounds

It comes very close to published data.

 

[blade]

Nope. Squared speed in feet per second times weight in pounds divides by constant gives FPE. The constant should be 450,436 (two times the acceleration of gravity times 7,000 - the amount of grains in a pound).

E=MV^2/2=WV^2/2G (M=W/G), so FPE aka ft/lbs = fps x fps x grains of weight / 450,436

 

[Brandon]

how about when you buy ammo and it isnt markes with fps, drop or exc. i just bought three boxes of 185 gr rem umc jhp from wally world 26 bux for 100 best price around they only had three boxes though does any one know the fps and drop @100 yrds and energy deposit? what about the winchester white box 165 grn fmj....is the 165 the weight of the bullet....i dont have a cronagraph (sp)? new shooter thx

 

[blade]

Brandon, bullet initial speed and energy depend on number of factors - primarily on the powder charge, bullet weight and barrel length (and many more, playing smaller role in a range of statistical error). The ammo manufacturers know for sure the only first two parameters for the given ammo. The third one they assume as a "standard average" within a range of guns the ammo is designed for. If you look at their charts, you'll see average fps and fpe. The gun manufacturers know for sure the only third parameter and assume first two as a "standard average" for the given gun within a range of acceptable ammo so you can see in the specs.

Try google you ammo to find out "standard average" fps and fpe. It's not a secret. For example, may look at this chart: http://www.tpquilmes.com.ar/info/Marshall & Sanow Stopping Power Stats.htm